Air conditioning and refrigeration systems for mobile vehicles such as conversion vans, recreational vehicles (RVs), buses, or trucks are known in the art. Typically, a generator set is used to provide a source of electrical power to various electrical systems or appliances within the vehicle, either to relieve the primary vehicle engine of the burden of powering these systems, or during times when the primary vehicle engine is not operating. Generator sets typically consist of an auxiliary engine and a generator or alternator. The various electrical systems of the vehicle, such as an electrically operated air conditioner, can then be powered by the generator set even when the vehicle engine is not operating. If an external source of electricity is available such as at an RV camp site, then electrical appliances including the air conditioner may be powered directly without the need to run either the vehicle engine or the auxiliary engine.
There are several drawbacks to this arrangement. An electrical air conditioning compressor is powered by electricity which must be generated by converting mechanical energy of the auxiliary engine into electrical energy for the compressor, which has a motor to convert the electrical energy back into mechanical energy. These multiple conversions represent a loss of efficiency in the system. Efficiency loss requires that the auxiliary engine and the generator have a larger capacity than would otherwise be necessary, and results in increased heat generation and reduced reliability. Increased capacity in the engine and the generator also adds to the cost and leads to a physically larger generator set, which may limit installation options. For example, it may be desired to install a generator set and air conditioner in the storage area of an RV. An excessively large generator set may prevent such installation due to a lack of available space, and may also reduce the amount of storage space available.
If, however, a mechanically driven compressor is used to avoid the multiple energy conversions, then a motor must be provided so as to allow the air conditioner to be powered from an external source of electricity. This also increases the size, increases the number of components, and again reduces reliability of the system.
It is clear that there has existed a long and unfilled need in the prior art for an air cooling system which reduces the number of components required, makes efficient use of the sources of power available, and is small enough to be installed in tight locations such as the available space in an RV. The present invention solves these and other shortcomings of the techniques known in the prior art.